Caster's True Name is Anastasia Nikolaevna Romanova (アナスタシア・ニコラエヴナ・ロマノヴァ, Anasutashia Nikoraevuna Romanova?). The youngest daughter of Nikolay II, the last Tsar of the Russian Empire. Swallowed by the turbulence of the Russian Revolutions, she was murdered at the Ipatiev House along with her family, servants and pet animals.
Fundamentally naive and innocent, but due a misanthropic disposition, she speaks in a dispassionate tone right after being summoned - a stage in which she still does not have faith in the Master. If one were to earn her trust, he will probably see her original lively, mischievous side. She left behind many pleasant episodes, such as taking her own picture by projecting the camera with a mirror... something that modern people would call a "selfie".
Many of her letters to her family still remain, which gives us a glimpse of her innocent side and deep affection to her family. Strictly speaking, the spirit or monster called Viy does not exist. It is a fictional monster that appeared in the horror novella "Viy", written by the Russian literary master Gogol. However, there are several folklores similar to Viy in Slav culture, and one can surmise that it was modeled after them.
The Viy that Anastasia is contracted with was a familiar in the possession of the Russian Empire. By means of his mystic eyes, he exposed all secrets, discovered weak points in fortresses and also dyed enemies in blood. However, it is impossible to either see or control him without the necessary talent───. It was only in the brink of death that Anastasia attained the qualifications to make a contract with him.
Anastasia is a beautiful girl, having long white hair and a fringe covering her icy blue eyes. She wears an ornate white gown and a white fur cape with gold designs and blue lining on. She is seen caressing a doll.
Little has been shown of Anastasia's personality, however it can be discerned she has a bitter, cold disposition. She seems to call Ritsuka Fujimaru, Mash, and da Vinci or perhaps those who oppose them as Rats, "Powerless living things that could do nothing but gnaw and multiply". Her belief of the world is that it is "cruelly, terribly cold", and that those who consider the mild surroundings as 'cold', should be shown a true hell.
Though she has shown to have some sense of small sympathy, as she warned Goldorf Musik that he was being backstabbed and used by the enemies. However, she only follows orders as is.
As the servant of Kadoc, she is shown to be slightly nicer underneath. She only acts distant due to her past and does not want her loved ones get hurt again, but once someone gets to know her, she is friendly, mischievous, and loves to play pranks.
Anastasia: The Permafrost EmpireEdit
Anastasia can manipulate ice. During the assault on Chaldea, her Noble Phantasm was used to freeze Chaldeas and render Chaldea unusable, with temperatures inside the facility dropping to below -100 degrees. Her Noble Phantasms are Viy Viy Viy and Sumerki Kremlin. Viy is the prized spirit of the Russian Empire which she is contracted with.
The version summoned by Kadoc into the Lostbelt is slightly distorted due to coming from the Greater History of Man. She claims to have been internally shifted to be similar to a Yaga despite maintaining her normal external appearance. Her history is distorted, an she has only a vague recollection of her family. She claims she has become a Servant of the Lostbelt, having gained a "twisted power" and the right to rule if Ivan should be defeated.